The City of Los Angeles asked for a new trial because, among other things, they subsequently discovered a videotape that allegedly conclusively establishes that the City wasn't liable. And maybe the video does indeed prove that fact.
But they didn't introduce that video at trial, and didn't even establish "due diligence" in trying to find out about it during discovery.
That's your lawyer's (and, here, client's) bad. No new trial for you.
Which means plaintiff gets to keep her $500,000 judgment.